This invention relates to improvements in food packaging, particularly to a food packaging material having the ability to retard oxidation of its contents.
One of the persistent problems that face the food industry is oxidation of foods during storage. Oxidation is particularly a problem with fats and oils. Fats and oils oxidize upon exposure to oxygen, and a rancid flavor is imparted to the fat, oil, or food containing the fat or oil. The oxidation of fats and oils appears to be a self-catalytic reaction. Once part of the fats or oil is oxidized, the rest oxidizes relatively quickly. Thus, preventing or retarding the oxidation in the first place is paramount.
To retard oxidation, anti-oxidants have been added to foods. For instance, BHA [(1,1-dimethylethyl)-4-methoxy phenol] and BHT [2,6-di-tert-butyl-para-cresol] are common anti-oxidant food additives. However, BHA is regarded as moderately toxic by ingestion, and even though BHT is considered to have low toxicity, the use in foods of either of these compounds is limited to 0.02%. While these compounds have contributed greatly to the food industry by reducing the amount of food that must be discarded, some consumers prefer foods without them.
Another anti-oxidant is glucose oxidase. Glucose oxidase is a well characterized enzyme that catalyzes the oxidation of glucose, consuming oxygen in the process. It has been proposed (see, e.g., U.S. Pat. No. 2,765,233 to Saret) to treat food wrappers with glucose oxidase to increase the oxidation resistance of food packaged in such wrappers. However, there are limits to the amount of glucose oxidase that can be applied to food wrappers by conventional techniques.